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4.4
Overall dimensions
Approximate measurements.
The maximum dimensions of the burner are given in (Fig. 2).
Bear in mind that inspection of the combustion head requires the
burner to be opened and the rear part withdrawn on the slide
bars.
The maximum dimension of the burner when open is give by
measurement I.
A
mm
234
4.5
Firing rates
The PRESS GBW Model burners can work in two ways: one-
stage and two-stage.
In one-stage operation, only one control device is provided: TL
(See the wiring diagram on page 25).
The burner fires in the 1st stage, where it remains for 7 seconds
before passing to the 2nd stage when commanded by the control
box 8) (Fig. 7 on page 13).
When the boiler temperature or pressure exceeds the values set
on the control device TL, the burner shuts down.
In two-stage operation, two control devices are provided: TL
and TR.
The burner fires in the 1st stage but passes to the 2nd stage only
if control device TR is closed. Once the temperature or pressure
value set on control device TR has been reached, the burner re-
turns to the 1st stage.
The burner shuts down only when the boiler temperature or pres-
sure exceeds the value set on control device TL, even if the burn-
er is still operating in the 1st stage.
Two-stage operation ensures reduced boiler temperature or
pressure fluctuation and consequently lower operating costs.
MINIMUM 1ST STAGE DELIVERY (MIN) must be selected with-
in the range of the values listed above the adjiacent diagram.
It is not necessary to know the pressure in the combustion cham-
ber in the 1st stage.
MAXIMUM 2ND STAGE DELIVERY (MAX) must be selected
within the range of the adjiacent diagram. This area is known as
the FIRING RATE and provides the maximum delivery of the
burner according to the combustion chamber pressure.
The work point may be found by plotting a vertical line from the
desired delivery and a horizontal line from the pressure in the
combustion chamber. The intersection of these two lines is the
work point which must lie within the FIRING RATE area.
Example:
if the PRESS GBW Model has a delivery of 21 kg/h at a combus-
tion chamber pressure of 4 mbar, the work point will be found on
the maximum pressure curve.
The firing rate value (Fig. 3) has been obtained
considering an ambient temperature of 20 °C, an
atmospheric pressure of 1013 mbar (approx. 0 m
WARNING
above sea level), and with the combustion head
adjusted as shown on page 27.
20033097
Technical description of the burner
B
C
205
292
140
D
E
F
185
473
Consult page 11, for operation at different surrounding tempera-
tures and/or altitudes.
The delivery of the burner to be coupled to the boiler must be se-
lected in the MAX. area - in other words, within the FIRING
RATE.
The burner can also operate in depression combustion cham-
bers.
PRESS GBW - MIN (1st stage) = 9 - 15 kg/h
10
GB
G
H
59
397
688
D320
Fig. 2
I
Tab. C
D425
Fig. 3
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